Device for the controlled emission of vapours

ABSTRACT

A device for the controlled emission of vapors comprising an inner tubular or box-shaped member which contains a volatile active substance and is permeable to vapor. The inner member is telescopingly arranged in a second tubular or box-shaped outer member so that the inner member may be entirely or partially sealed by the outer member. The inner member contains a porous container which may be filled with the active substance and the maximum pore width of which is 30 microns. The container is preferably made of polyethylene. The inner member may either be apertured or be made of a porous material.

[ 1 Nov. 6, 1973 1 DEVICE FOR THE CONTROLLED EMISSION or VAPOURS [75]Inventors: Serge Hoek; Wilhelm Buhren, both of Amsterdam, Netherlands[73] Assignee: U.S. Philips Corporation, New York, NY.

[22] Filed: Sept. 13, 1971 [21] Appl. No.: 180,028

[30] Foreign Application Priority Data FOREIGN PATENTS OR APPLICATIONS309,854 3/1918 Germany ..239/563 204,836 8/1959 Austria ..239/563Primary ExaminerRichard A. Schacher Assistant Examiner-Andres KashnikowAttorneyFrank R. Trifari [57] ABSTRACT A device for the controlledemission of vapors comprising an inner tubular or box-shaped memberwhich contains a volatile active substance and is permeable to vapor.The inner member is telescopingly arranged in a second tubular orbox-shaped outer member so that the inner member may be entirely orpartially sealed by the outer member. The inner member contains a porouscontainer which may be filled with the active substance and the maximumpore width of which is 30 microns. The container is preferably made ofpolyethylene. The inner member may either be apertured or be made of aporous material.

2 Claims, 2 Drawing Figures PATENTED Fig.1

- I I I I 9 w I: 2 M :3 :i 7 LJTT n u n 2 f 5E5: W if: 1:: I 3 3 3 i a Zm F lg 2 INVENTORS SERGE HOEK WILHELM BUHREN BY 4 gent 1 DEVICE FUR THECONTROLLED EMISSION F VAPOURS The invention relates to a device for thecontrolled emission of vapours which comprises telescoping inner andouter box-shaped or tubular members, the inner member being permeable tovapour, forming a container for a carrier comprising a volatile activesubstance, and being closed at both ends, whilst the outer member isclosed at one end and is provided with guiding means for the innermember which may at least partly be covered by the outer member.

in a known device of the said type, the inner member may be filled withan active substance in the form of a powder or a tablet. When an activesubstance in the liquid state is used a cartridge impregnated with theliquid is arranged in the inner member. In the latter embodiment thecapacity of the device is restricted to the amount of liquid which thecartridge is capable of taking up. Manufacturing and impregnating thecartridge provides difficulty when the device is manufactured bymass-production methods.

It is an object of the invention to provide a device for the controlledemission of vapours which is particularly suited for volatile activesubstances in the liquid or viscous state, has a comparatively largecapacity and the useful life of which may be determined by the amount ofliquid with which it is filled.

According to the invention, this object is mainly achieved in that thecarrier is a porous container which may be filled with a liquid activesubstance and the maximum pore width of which is 30 microns.

By using a porous container as a carrier for an active substance in theliquid or viscous state, the filling up may take place directly andsimply; this enables the filling process to be automatized. In addition,the container may be filled with an active substance which is liquid atan elevated temperature and solidifies at a lower temperature. In orderto prevent leakage of the container the maximum pore width should ingeneral not exceed in 30 microns. The ultimate choice of the pore widthis related to the viscosity of the active substance. The useful life ofthe device may be influenced by the dimensions of the container and/orby the extent to which it is filled.

The container may be made from any suitable porous material, for examplea porous glass or a porous ceramic or synthetic material. However, in apreferred embodiment of the device according to the invention thecontainer is made of polyethylene. This material may be simply worked toform a container, especially a tubular or box-shaped container, andmoreover has a high chemical resistance, so that it is suitable for mostvolatile chemical substances.

The vapour-permeable inner member which encloses the container may bemade from a compact gas-tight material, for example a metal, a syntheticmaterial or paper board, and may be apertured in known manner. In afurther preferred embodiment of the device ac cording to the invention,the inner member is porous and made of a low-pressure polyethylenehaving a high specific weight. Owing to the high mechanical resistanceof the polyethylene, wear of the inner member due to the relativedisplacement of the inner and outer members is very slight.

The porous inner member may enclose the container with a certain amountof clearance, in which case the maximum pore width of the inner memberis not critical and need only be sufficient to enable the vapours topass. In order to obtain a maximum volume of the container with givendimensions of the inner member, in another preferred embodiment of thedevice according to the invention the outer surface of the containerengages the inner surface of the inner member, the pore width of theinner member exceeding the maximum pore width of the container. Owing tothe greater pore width of the inner member diffusion of the activesubstance into the wall of the inner member is prevented.

Embodiments of the invention will now be described, by way of example,with reference to the accompanying diagrammatic drawings, in which:

FIG. 1 is a longitudinal sectional view of an embodiment of a deviceaccording to the invention, and

FIG. 2 is a longitudinal sectional view of another embodiment of such adevice.

Referring now to FIG. 1, the device shown comprises telescoping innerand outer tubular or box-shaped members 21 and 23 respectively. Theinner member 21 is hermetically sealed at both ends by a hood 25 and bya bottom 27 having a rim 2% respectively. The outer member 23 is at oneend provided with a closing wall 31, and at the opposite, open end witha ring 33 which preferably is made of a synthetic material and fittinglyencloses the inner member 21.

In the inner member 21 there is placed a porous container 35, which inthe embodiment shown in tubular and is sealed at both ends by the hood25 and the bottom 27. The container 35, which has a maximum pore widthof 30 microns, may be filled entirely or partially with a liquid orviscous active substance 37 to be vaporized. The porous material may bea porous glass or a porous ceramic or synthetic material. However, thecontainer 35 is preferably made of polyethylene, which has a highchemical resistance.

The inner member 21 is permeable to vapour and may be entirely orpartially covered by the gas-tight outer member 23. The inner member 21may be made of any suitable material, for example paper board, a metalor a synthetic material, and may be apertured in known manner.Preferably, however, the inner member 21 is porous and made oflow-pressure polyethylene having a high specific weight, which materialhas a high resistance to wear.

In the embodiment shown in FlG. l, the outer surface of the container 35contacts the inner surface of the inner member 21, so that for any innermember the volume of the container is a maximum. If in this embodiment aporous inner member is used, the pore width of the inner member must begreater than the maximum pore width of the container; this prevents thediffusion of the active substance into the wall of the porous innermember.

In the embodiment shown in FIG. 2, there is a clearance between thecontainer 35 and the inner member 21; when a porous inner member isused, its maximum pore width is not critical and need only be chosen soas to permit the emission of vapours.

The outer member 23 may be made of any suitable vapour-impermeablematerial.

During the relative displacements of the inner and outer members, thering 33 forms a guiding means for the inner member 21 and, inconjunction with the rim 29 of the bottom 27, a stop preventing anundesirable complete separation of the two members. In the fully closedposition of the device, the ring 33 in conjunction with the hood 25prevents vapours from escaping. Since the ring 33 fittingly encloses theinner member 21 the two members are held in any relative intermediateposition by frictional forces alone, the part of the inner member 21 notexposed to the ambient atmosphere being sealed by the ring 33.

In the embodiments described, the inner and outer members aretelescoping. As an alternative, the members may be relatively rotatable.However, telescoping members provide a greater control range and bettersealing.

What is claimed is:

l. A device for the controlled emission of vapors comprising an outertubular member impermeable to vapor and closed at one end thereof andopened at its other end, a hermetically sealed inner tubular membertelescopingly carried within said outer member, said inner member beingpermeable to vapor, a closed porous container carried within said innermember for carrying a liquid active substance, the maximum pore diameterof any of the pores of said closed container being 30 microns and quidemeans carried by said outer member for guiding said inner membertherein, said inner member being porous and made of'lowpressurepolyethylene having a high specific weight, the outer surface of saidcontainer engaging the inner surface of the inner member, the pore widthof the inner member being greater than the maximum pore width of thecontainer.

2. The device as claimed in claim 1, wherein said inner and outermembers are made of polyethylene.

1. A device for the controlled emission of vapors comprising an outertubular member impermeable to vapor and closed at one end thereof andopened at its other end, a hermetically sealed inner tubular membertelescopingly carried within said outer member, said inner member beingpermeable to vapor, a closed porous container carried within said innermember for carrying a liquid active substance, the maximum pore diameterof any of the pores of said closed container being 30 microns and quidemeans carried by said outer member for guiding said inner membertherein, said inner member being porous and made of low-pressurepolyethylene having a high specific weight, the outer surface of saidcontainer engaging the inner surface of the inner member, the pore widthof the inner member being greater than the maximum pore width of thecontainer.
 2. The device as claimed in claim 1, wherein said inner andouter members are made of polyethylene.